Laboratory Results: How Blood "works"

Laboratory results: How blood "works"

The blood is the most important body fluid and contains up to 4.5 liters in women and up to five liters in men (with a body weight of 70 kg each). Blood consists of solid (blood cells) and liquid (plasma) substances, and the functions of the blood are based on these components.

One of the most important tasks of the blood is the transport of oxygen and nutrients to the peripheral tissues and cells. On the other hand, carbon dioxide and metabolic products are also removed via the blood. In addition, blood also functions as a transport medium for the body's heat regulation, and it fulfills a number of other tasks in the context of signal transmission (e.g. hormonal system) and the body's immune defense.

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• What is blood made of?
• Red blood cells (erythrocytes)
• White blood cells (leukocytes)
• Blood platelets (thrombocytes)
• Where is the blood made?
• ">What is blood plasma?

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What is blood made of?

Blood is not just a liquid. In medicine, this most important human body fluid is viewed as an independent organ. Accordingly, a blood transfusion, for example, also has the status of an organ transplant.

The tasks of the blood in the body are carried out by the various blood components:

• Red blood cells: carry oxygen and carbon dioxide.
• White blood cells: protect the body from bacteria, fungi, viruses and parasites.
• Platelets: activate blood clotting in injuries.
• Blood plasma: transports nutrients and metabolic products and plays an important role in blood clotting.

Red blood cells (erythrocytes)

The red color of blood is solely due to its solid (cellular) components - the red blood cells (erythrocytes). These are cells floating in the bloodstream that look like small discs under the microscope.

The most important function of red blood cells is to transport oxygen. For this purpose, a lively gas exchange takes place in the lungs, whereby the erythrocytes are enriched with oxygen. They are now distributed throughout the body via the bloodstream and in this way supply the cells and tissues with oxygen.

On the other hand, the oxygen used in the blood is transported back to the lungs in the form of carbonic acid and exhaled as CO ₂ (carbon dioxide). In this sense, the lungs are an important elimination organ for excess acids in the body.

White blood cells (leukocytes)

The white blood cells (leukocytes) are inflammatory cells. Their function is to defend the body against bacteria, viruses, parasites and fungi. There are certain types of leukocytes, each with a different task, but these cells work together (interact) intensively:

• Granulocytes: Defense against microorganisms (bacteria), infected cells, foreign substances (e.g. pollen).
• Lymphocytes (often also immune cells): formation of antibodies and killing infected cells.
• Monocytes (also scavenger cells): Interaction with granulocytes and lymphocytes.

Blood platelets (thrombocytes)

In addition to the red and white blood cells, there are also blood platelets (thrombocytes). However, these are not whole cells, but rather cell fragments necessary for blood clotting.

Where is the blood made?

In healthy adults, the main production site for blood cells and platelets is the bone marrow. Lymphocytes are an exception. In adults, these are formed in the bone marrow (B lymphocytes) and thymus (T lymphocytes). They are then transported to the secondary lymphatic organs:

• Spleen,
• Lymph nodes,
• Tonsils (tonsils),
• Intestinal mucosa etc.

What is blood plasma?

The blood plasma is the fluid in which the blood cells swim. This highly complex liquid contains a large number of dissolved substances and has a wide variety of functions.

The composition of the blood plasma is complex, so the body can only tolerate minor fluctuations in the ingredients. Gross changes in blood chemistry - pH value, electrolytes, etc. can lead to life-threatening conditions such as cardiac arrhythmias or even heart failure.

In the first place of the various tasks of the plasma is the transport. This time not from gases (see red blood cells), but from nutrients and metabolic products. The functions of blood plasma include:

Transport of nutrients

• Carbohydrates in the form of blood sugar (glucose),
• Dietary protein in the form of amino acids,
• Fats in the form of blood fats (cholesterol and triglycerides): Fats in particular require specialized protein-bound forms of transport so that no fat droplets form in the blood. Accordingly, the fats in the blood are bound to proteins and transported in the form of lipoproteins (HDL, LDL, etc.).
• Removal of metabolic end products to the excretory organs liver and kidneys: urea, uric acid, bilirubin, creatinine etc.

Transport of coagulation factors

Blood clotting is mediated by a large number of plasma proteins produced in the liver, and this whole system functions within a complex interplay between plasma, platelets and vessel walls (called the endothelium).

Acid / base and electrolyte balance

A balanced acid / base balance in the blood is also important for health. The electrolytes (sodium, potassium, chloride, magnesium, calcium, phosphate) must also be in a state of equilibrium that is precisely controlled by the body.

Other transport functions

Hormones, drugs, inflammatory substances, trace elements, vitamins and much more are also carried in the blood. After all, the activity of special enzymes in the blood reflects the function of organs (liver, heart, muscles, bones, etc.).

You can also find information under Blood: Basic Info.